[PATCH] md: Change md/bitmap file handling to use bmap to file blocks-fix

Fix problems with new bmap based access to bitmap files.

1/ When not using a file based bitmap, attach a NULL list of buffers
   to each page so the common free_buffer routine can cope.
2/ Use submit_bh to read as well as write, rather than vfs_read.
   This makes read and write more symetric.
3/ sync the file before reading, to ensure that the page cache has no
   dirty pages that might get written out later.

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 23 insertions, 24 deletions

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index bedd66e9e8ac..ebbd2d856256 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -247,6 +247,8 @@ static struct page *read_sb_page(mddev_t *mddev, long offset, unsigned long inde
 
                 if (sync_page_io(rdev->bdev, target, PAGE_SIZE, page, READ)) {
                         page->index = index;
+                        attach_page_buffers(page, NULL); /* so that free_buffer will
+                                                          * quietly no-op */
                         return page;
                 }
         }
@@ -349,11 +351,8 @@ static struct page *read_page(struct file *file, unsigned long index,
 {
         struct page *page = NULL;
         struct inode *inode = file->f_dentry->d_inode;
-        loff_t pos = index << PAGE_SHIFT;
-        int ret;
         struct buffer_head *bh;
         sector_t block;
-        mm_segment_t oldfs;
 
         PRINTK("read bitmap file (%dB @ %Lu)\n", (int)PAGE_SIZE,
                         (unsigned long long)index << PAGE_SHIFT);
@@ -364,18 +363,6 @@ static struct page *read_page(struct file *file, unsigned long index,
         if (IS_ERR(page))
                 goto out;
 
-        oldfs = get_fs();
-        set_fs(KERNEL_DS);
-        ret = vfs_read(file, (char __user*) page_address(page), count, &pos);
-        set_fs(oldfs);
-
-        if (ret >= 0 && ret != count)
-                ret = -EIO;
-        if (ret < 0) {
-                put_page(page);
-                page = ERR_PTR(ret);
-                goto out;
-        }
         bh = alloc_page_buffers(page, 1<<inode->i_blkbits, 0);
         if (!bh) {
                 put_page(page);
@@ -403,12 +390,22 @@ static struct page *read_page(struct file *file, unsigned long index,
 
                         bh->b_end_io = end_bitmap_write;
                         bh->b_private = bitmap;
+                        atomic_inc(&bitmap->pending_writes);
+                        set_buffer_locked(bh);
+                        set_buffer_mapped(bh);
+                        submit_bh(READ, bh);
                 }
                 block++;
                 bh = bh->b_this_page;
         }
-
         page->index = index;
+
+        wait_event(bitmap->write_wait,
+                   atomic_read(&bitmap->pending_writes)==0);
+        if (bitmap->flags & BITMAP_WRITE_ERROR) {
+                free_buffers(page);
+                page = ERR_PTR(-EIO);
+        }
 out:
         if (IS_ERR(page))
                 printk(KERN_ALERT "md: bitmap read error: (%dB @ %Lu): %ld\n",
@@ -1415,15 +1412,20 @@ int bitmap_create(mddev_t *mddev)
                 return -ENOMEM;
 
         spin_lock_init(&bitmap->lock);
+        atomic_set(&bitmap->pending_writes, 0);
+        init_waitqueue_head(&bitmap->write_wait);
+
         bitmap->mddev = mddev;
 
         bitmap->file = file;
         bitmap->offset = mddev->bitmap_offset;
-        if (file) get_file(file);
-
-        /* Ensure we read fresh data */
-        invalidate_inode_pages(file->f_dentry->d_inode->i_mapping);
-
+        if (file) {
+                get_file(file);
+                do_sync_file_range(file, 0, LLONG_MAX,
+                                   SYNC_FILE_RANGE_WAIT_BEFORE |
+                                   SYNC_FILE_RANGE_WRITE |
+                                   SYNC_FILE_RANGE_WAIT_AFTER);
+        }
         /* read superblock from bitmap file (this sets bitmap->chunksize) */
         err = bitmap_read_sb(bitmap);
         if (err)
@@ -1446,9 +1448,6 @@ int bitmap_create(mddev_t *mddev)
 
         bitmap->syncchunk = ~0UL;
 
-        atomic_set(&bitmap->pending_writes, 0);
-        init_waitqueue_head(&bitmap->write_wait);
-
 #ifdef INJECT_FATAL_FAULT_1
         bitmap->bp = NULL;
 #else